Search results for "Mphi"

Is there a role for antioxidant carotenoids in limiting self-harming immune response in invertebrates?

2007

Innate immunity relies on effectors, which produce cytotoxic molecules that have not only the advantage of killing pathogens but also the disadvantage of harming host tissues and organs. Although the role of dietary antioxidants in invertebrate immunity is still unknown, it has been shown in vertebrates that carotenoids scavenge cytotoxic radicals generated during the immune response. Carotenoids may consequently decrease the self-harming cost of immunity. A positive relationship between the levels of innate immune defence and circulating carotenoid might therefore be expected. Consistent with this hypothesis, we show that the maintenance and use of the prophenoloxidase system strongly cor…

No room for males in caves: Female-biased sex ratio in subterranean amphipods of the genus Niphargus.

2021

Sex allocation theory predicts that the proportion of daughters to sons will evolve in response to ecological conditions that determine the costs and benefits of producing each sex. All else being equal, the adult sex ratio (ASR) should also vary with ecological conditions. Many studies of subterranean species reported female-biased ASR, but no systematic study has yet been conducted. We test the hypothesis that the ASR becomes more female-biased with increased isolation from the surface. We compiled a data set of ASRs of 35 species in the subterranean amphipod Niphargus, each living in one of three distinct habitats (surface-subterranean boundary, cave streams, phreatic lakes) representing…

Sexual differences in larval life history traits of acanthocephalan cystacanths

2006

Sexual differences in life history traits, such as size dimorphism, presumably arise via sexual selection and are most readily observed in adults. For complex life-cycle parasites, however, sexual selection may also have consequences for larval traits, e.g., growth in intermediate hosts. Two acanthocephalan species (Acanthocephalus lucii and Echinorhynchus borealis) were studied to determine, whether larval life histories differ between males and females. The size of female A. lucii cystacanths had a much stronger relationship with intermediate host size than males, suggesting females invest more in growth and are consequently more limited by resources. No relationship between host size and…

Effects of feminizing microsporidia on the masculinizing function of the androgenic gland in Gammarus duebeni

2013

Feminizing parasites enhance their vertical transmission to the host offspring by converting genetic male hosts into phenotypic females. Crustacea are the only invertebrates where sexual differentiation is controlled by a specialised endocrine organ, the androgenic gland, rather than by the gonads. We showed that a feminizing microsporidian Microsporidium sp. inhibits androgenic gland differentiation. We investigated the effect of Microsporidium sp. and a second feminizing microsporidium, Nosema granulosis, on the masculinizing function of the androgenic gland in Gammarus duebeni. Androgenic gland implants had a masculinizing effect on the sexual characteristics and sexual behaviour of reci…

Contrasting parental roles shape sex differences in poison frog space use but not navigational performance

2022

Sex differences in vertebrate spatial abilities are typically interpreted under the adaptive specialization hypothesis, which posits that male reproductive success is linked to larger home ranges and better navigational skills. The androgen spillover hypothesis counters that enhanced male spatial performance may be a byproduct of higher androgen levels. Animal groups that include species where females are expected to outperform males based on life-history traits are key for disentangling these hypotheses. We investigated the association between sex differences in reproductive strategies, spatial behavior, and androgen levels in three species of poison frogs. We tracked individuals in natura…

Molecular phylogeny of Malagasy poison frogs, genus Mantella (Anura: Mantellidae): homoplastic evolution of colour pattern in aposematic amphibians

2002

Abstract We studied the evolution of colour pattern in Malagasy poison frogs, genus Mantella , a group of diurnal and toxic frogs endemic to Madagascar. Based on a phylogeny reconstructed using 1130 bp of the mitochondrial 16S rRNA gene, the genus can be divided into five species groups. Within some of these groups, interspecific genetic divergences were very low (1.2–2.8% sequence divergence) while colour patterns were markedly different. In contrast, Mantella madagascariensis and M . baroni , two species which show extremely similar dorsal coloration patterns, were not included in the same clade. This conclusion was supported by high bootstrap values and by significant rejection of altern…

2018

Marine sponges are a very attractive and rich source in the production of novel bioactive compounds. The sponges exhibit a wide range of pharmacological activities. The genus Amphimedon consists of various species, such as viridis, compressa, complanata, and terpenensis, along with a handful of undescribed species. The Amphimedon genus is a rich source of secondary metabolites containing diverse chemical classes, including alkaloids, ceramides, cerebrososides, and terpenes, with various valuable biological activities. This review covers the literature from January 1983 until January 2018 and provides a complete survey of all the compounds isolated from the genus Amphimedon and the associate…

Energetically costly precopulatory mate guarding in the amphipod Gammarus pulex: causes and consequences

2003

Precopulatory mate guarding (PCMG) is thought to have evolved as a male mating strategy in species in which female receptivity is limited to a short time. It is common among crustaceans, and energetic costs associated with PCMG are thought to promote size-assortative pairing in such species, although direct evidence is lacking. Using both field surveys and laboratory experiments, we assessed the energetic costs of PCMG in Gammarus pulex and investigated their possible causes. Energetic costs were measured as differences in lipid and glycogen reserves. In field-collected samples, size-corrected lipid and glycogen reserves of paired males were both significantly higher than those of unpaired …

Hyaluronic Acid-Based Micelles as Ocular Platform to Modulate the Loading, Release, and Corneal Permeation of Corticosteroids

2017

The aim of this work is to prepare hyaluronic acid-based micelles as a platform to load corticosteroid drugs and to improve their corneal permeation after administration on the ocular surface. Three amphiphilic derivatives of hyaluronic acid (HA) are synthesized using different amounts of hexadecylamine (C16 -NH2 ). HAC16 a, HAC16 b, and HAC16 c derivatives are able to form micelles by the cosolvent evaporation method and to entrap corticosteroids (dexamethasone, triamcinolone, triamcinolone acetonide). HAC16 a and HAC16 b micelles show the best results in terms of drug loading and particle size. They are also able to improve drug release compared to free drug solution or suspension. In add…

In Silico Design Enables the Rapid Production of Surface-Active Colloidal Amphiphiles

2020

A new technology platform built on the integration of theory and experiments to enable the design of Janus colloids with precision control of surface anisotropy and amphiphilicity could lead to a disruptive transformation in the next generation of surfactants, photonic or phononic materials, and coatings. Here, we exploit molecular dynamics (MD) simulations to guide the rational design of amphiphilic polymer Janus colloids by Flash NanoPrecipitation (FNP), a method capable of the production of colloids with complex structure without the compromise of reduced scalability. Aided by in silico design, we show in experiments that amphiphilic Janus colloids can be produced using a unique blend of…